I just bought a 9760. A friend told me that I really need auto steer with a 635 head. So I checked with the dealer about auto steer. He told me about $10,000. I said "outa the question". My buddy says if you go used you can get into the whole deal for about 4500-5000. Is this true? Can it be adapted to 7720 and 8330 tractors? If I can get into this reliably for less than 5k I would certainly consider it (35 ft head really looks big to me). Can anyone give me some advice?